The default Prolog mode for GNU-Emacs can be activated by adding the following rules to your Emacs initialisation file:
(setq auto-mode-alist (append '(("\\.pl" . prolog-mode)) auto-mode-alist)) (setq prolog-program-name "swipl") (setq prolog-consult-string "[user].\n") ;If you want this. Indentation is either poor or I don't use ;it as intended. ;(setq prolog-indent-width 8)
Unfortunately the default Prolog mode of GNU-Emacs is not very good. There are several alternatives though: